As a by-product of the new Demographic/Health Surveys project, an opportunity has developed to conduct a large-scale, experimental field evaluation of different approaches to the measurement of many variables normally collected in such surveys, and to contribute to a number of methodological issues. These issues cover such topics as: accuracy of data collected in a truncated birth history; the usefulness of collecting information on fetal deaths for improving the counts of births and infant deaths; the feasibility of obtaining five-year histories on contraceptive practice, breastfeeding, postpartum amenorrhea and abstinence, exposure to the risk of pregnancy, migration and residence, and women's employment. We also propose to evaluate different approaches to the collection of data relevant to estimating the prevalence of immunization and diarrhea and its treatment for children under five. The design of the experiment involves conducting two national probability sample surveys. One survey includes 5,000 interviews with women of reproductive age that will be conducted with the standard core questionnaire developed for the general survey project; the other survey features interviews with 3,000 women, based on an experimental questionnaire. Both questionnaires will be administered by the same interviewers in the same period of time. The fieldwork and production of data tapes will be carried out by Westinghouse Health Systems as part of the Demographic/Health Surveys project; the current proposal is to support the analysis of the methodological component. The goal is to enhance the value of future surveys of fertility, family planning, and infant and child health.